Résumé
esticide use became one of the main matters in the agriculture field, and that is due to the off-target spray particles causes environmental, health and economic problems. Spraying quality could be optimized by assessing off-target volumes, and thus help farmers to improve their farming performances. This work aimed to develop an optical sensor based on a RIB waveguide design in order to characterize the quantity and distribution of a liquid spray deposit. We assumed that the light guidance properties of these sensors would undergo a modification when spraying droplets are deposited on their surface. This phenomenon results from partial evanescent wave absorption by the water present in the pesticides which leads to a decrease in the transmitted intensity at the waveguide output. Using different droplet volumes (from 0,1 to 2,5 μl), we studied on an optical bench theinfluence of a range of deposits at the guide center. As expected, the result was a gradual decrease in the output intensity signal due to the water absorption of the evanescent field, and this proportionally to the droplet volume; the bigger the droplet, the greater the loss in output intensity. We tested the waveguide on a spectral analysis bench in order to highlight the light absorption at the specific water wavelength using the output spectrum. The result showed an absorption at 1450μm wavelength wich is one of the water wavelength absorption. These first results demonstrate the potential of RIB waveguide sensors to accurately quantify droplet deposits. Our future work should focus on improving the waveguide architecture in order to estimate deposited volumes and also the number of deposited droplets.